Question

1.Determinati numarul moleculelor care se gasesc in : a.1.12 m cubic O2 b. 0.5 kmoli o2
2. Concentratia procentuala a solutiei obtinute prin amestecarea a 200 g solutie acid sulfuric de concentratie 30% cu 400 g apa disilata.

Answer 1

a) n = 1,12/22,4 = 0,05 = 50 moli O2
nr. molec = 50·6,023·10²³ = 3,0115·10²⁵ molecule
b) 0,5kmoli = 50 moli ⇒ idem a)
2. solutia initiala de H2SO4 : msi = 200g; ci = 30% ⇒ md = 60g
+ 400g apa
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solutia finala : ms = 600g   md = 60g    c = 60·100/600 = 10%

Answer 2

1) 1,12m^3=1120dm^3=1120L
In c.n ,Vm=22,4L
Nr moli O2=1120/22,4=50moli
NA=6,023*10^23 particule
Nr molecule O2 =3,0115*10^25

0,5kmoli =500moli
Nr molecule O2=3,0115*10^26

2)md=cms/100=200*30/100=60g

c1=md*100/ms'=6000/600=10%